Yes that can be frustrating. Sorry if my remark came off as flippant. The shared view helped a great deal.
The additional space characters are being introduced from multiple places:
(1) The formula itself
Whoever wrote it left some spaces in some of the strings (a string is anything with quotes around it). I’m not sure if those were intentional or not, but here it is without those additional spaces:
LOWER( {URL} & "?utm_medium=" & {Medium} & "&utm_source=" & {Source} & "&utm_campaign=" & {Campaign Name} & "utm_content=" & {Content})
(2) Single select fields that the formula relies on
Both “Source” and “Medium” have space characters added to some of the values - for example, “twitter” is "twitter ". There could be other fields with the same issue.
You could either keep a closer eye on any fields that the formula relies on, or build your formula to correct for user error. To remove spaces, you’d use TRIM, which removes leading or trailing space characters, or you could use a function like SUBSTITUTE to automatically replace any space characters with a hyphen (as you have with the “Campaign Name” field).
Examples:
TRIM({Source})
"Twitter " => “Twitter”
SUBSTITUTE({Content}, " ", “-”)
“Post With Image” => “Post-With-Image”
Putting it all together, you’d end up with this:
SUBSTITUTE( LOWER( TRIM({URL}) & "?utm_medium=" & TRIM({Medium}) & "&utm_source=" & TRIM({Source}) & "&utm_campaign=" & TRIM({Campaign Name}) & "utm_content=" & TRIM({Content}) )," ","-")
